3 



It has been stated that the fragrance of flowers 

 depends upon the volatile oils they contain ; and these 

 oils, by their constant evaporation, surround the 

 flower with a kind of odorous atmosphere ; which, at 

 the same time that it entices larger insects, may pro- 

 bably preserve the parts of fructification from the ra- 

 vages of the smaller ones. Volatile oils, or odorous 

 substances, seem particularly destructive to these mi- 

 nute insects and animalcules which feed on the sub- 

 stance of vegetables ; thousands of aphides may be 

 usually seen in the stalk and leaves of the rose ; but 

 none of them are ever observed on the flower. Cam- 

 phor is used to preserve the collections of naturalists. 

 The woods that contain aromatic oils are remarked 

 for their indestructibility ; and for their exemption 

 from the attacks of insects : this is particularly the 

 case with the cedar, rose- wood, and cypress. The 

 gates of Constantinople, which were made of this last 

 wood, stood entire from the time of Constantine, their 

 founder, to that of Pope Eugene IV. a period of 1 10O 

 years. 



The petals of many flowers afford saccharine and 

 mucilaginous matter. The white lily yields mucilage 

 abundantly ; and the orange lily a mixture of mucil- 

 age and sugar ; the petals of the convolvulus afford 

 sugar, mucilage, and albuminous matter. 



The chemical nature of the colouring matters of 

 flowers has not as yet been subject to any very accu- 

 rate observation. These colouring matters, in gen- 

 eral, are very transient, particularly the blues and 

 reds j alkalies change the colours of most flowers to 

 green, and acids to red. An imitation of the colour- 



